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United States Patent |
5,238,166
|
Schwarstein
,   et al.
|
August 24, 1993
|
Sealing arrangement for retaining liquid lubricant in selected areas of
a machine
Abstract
A sealing assembly for regulating the flow of lubricant to a rotating shaft
and to the bearings which support it. The shaft is supported on
rolling-contact bearings to which are coupled bearing collars. The bearing
collars serve as spray-off edges for removing lubricant from the bearings,
which after removal, is received in a groove formed between the bearing
and a seal member. This groove is in liquid communication with an opening
to the surface of the shaft which, as it rotates, centrifuges lubricant
from the groove. The shaft is encircled by the seal member which includes
several chambers for receiving lubricant sprayed off the shaft at several
spray-off edges. At the end of the seal member furthest from the
rolling-contact bearings an outlet for the lubricant of the same size as
the inlet is provided, thereby reducing pressure differences between the
inlet and the outlet.
Inventors:
|
Schwarstein; Egbert (Nuremberg, DE);
Holzel; Helmut (Thalmassing, DE)
|
Assignee:
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Siemens Aktiengesellschaft (Munich, DE)
|
Appl. No.:
|
978066 |
Filed:
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November 18, 1992 |
Foreign Application Priority Data
Current U.S. Class: |
277/412; 384/144; 384/480 |
Intern'l Class: |
F16J 015/48; F16C 033/74 |
Field of Search: |
277/53,55,56,68,25,67,70,71,79
384/144,145,146,480,474
|
References Cited
U.S. Patent Documents
2245281 | Jun., 1941 | Klopak | 277/67.
|
2281905 | May., 1942 | Young | 286/5.
|
2524124 | Oct., 1950 | Gyana | 277/67.
|
4462515 | Sep., 1983 | Malott | 277/67.
|
4513975 | Oct., 1950 | Hauser et al. | 277/75.
|
Foreign Patent Documents |
1475600 | Jan., 1969 | DE.
| |
8715621 | Mar., 1988 | DE.
| |
Other References
Machine Design--The Electric Motor Book, Chapter 8, pp. 42-43, James
Penney, Westinghouse Electric Corp., Buffalo, N.Y., 1961.
Kugellager-Zeitschrift, No. 4, 1961, pp. 79, 83.
|
Primary Examiner: Cuchlinski, Jr.; William A.
Assistant Examiner: DePumpo; Daniel G.
Attorney, Agent or Firm: Kenyon & Kenyon
Parent Case Text
This application is a continuation of application Ser. No. 07/759,895,
filed Sep. 13, 1991, now abandoned.
Claims
What is claimed is:
1. A sealing apparatus for retaining liquid lubricant in selected areas of
machine, comprising:
a shaft rotatably mounted, for rotation relative to a stationary housing,
wherein the shaft defines a first axis central to the shaft, and wherein
the shaft further defines inlet and outlet portions separated axially
along the shaft, and wherein the shaft diameter increases in a plurality
of discrete gradations between the inlet and outlet portions of the shaft;
at least one rolling-contact bearing, to be lubricated by the liquid
lubricant, mounted adjacent the inlet portion of the shaft within the
stationary housing for supporting the rotatably mounted shaft therein,
wherein each rolling-contact bearing defines a second axis central to the
roller bearing;
a bearing collar adjacent each rolling-contact bearing and defining a
protrusion extending away from the first axis and toward the second axis,
said protrusion being located on the end of the bearing collar adjacent
the inlet portion of the shaft;
a labyrinth seal member mounted around the shaft, wherein the labyrinth
seal member defines, adjacent to the inlet portion of the shaft, an
annular rim which is separated by a distance along the axis of the shaft
from the protrusion of each bearing collar, wherein at least a portion of
said annular rim and a corresponding portion of said protrusion are
located substantially equidistant from said first axis, said separation
defining a radially extending inlet for the liquid lubricant;
a plurality of chambers disposed within the labyrinth seal member, wherein
the chambers are disposed between the inlet and outlet portions of the
shaft and open onto the surface of the shaft, for receiving lubricant
removed from the shaft;
at least one drain port for the liquid lubricant in liquid communication
with at least one of the chambers defined within the labyrinth seal
member; and
an outlet for the liquid lubricant of a diameter substantially equal to
that of the inlet for the liquid lubricant.
2. The sealing arrangement according to claim 1, wherein the labyrinth seal
member further defines, adjacent the annular rim defined by the labyrinth
seal member and in liquid communication with the inlet, a groove for
collecting liquid lubricant, said groove being dimensioned based on the
quantity of liquid lubricant that is centrifuged off at the inlet through
the rotation of the shaft.
3. The sealing apparatus according to claim 1, wherein the size of each
chamber in the labyrinth seal member is dimensioned to be large enough to
accommodate the maximum amount of liquid lubricant present, at each
chamber's respective location along the shaft, during operation of the
machine.
4. The sealing apparatus of claim 1, wherein the outlet for the liquid
lubricant is defined between the labyrinth seal member and a protrusion
from the shaft.
5. The sealing apparatus according to claim 1, further comprising a
plurality of drain ports, each drain port being in fluid communication
with a respective chamber defined within the labyrinth seal member for
receiving lubricant therefrom.
6. The sealing apparatus according to claim 1, wherein at least one of the
rolling-contact bearings is a rolling-contact bearing of the N type of
construction.
7. The sealing apparatus according to claim 2, wherein the size of each
chamber in the labyrinth seal member is dimensioned to be at least large
enough to accommodate the maximum amount of liquid lubricant present, at
each chamber's respective location along the shaft, during operation of
the machine.
8. A sealing apparatus for retaining liquid lubricant in selected areas of
a machine, comprising:
a shaft rotatably mounted, for rotation relative to a stationary housing,
wherein the shaft defines a first axis central to the shaft, wherein the
shaft further defines inlet and outlet portions separated axially along
the shaft, and wherein the shaft diameter increases in a plurality of
discrete gradations between the inlet and outlet portions of the shaft,
wherein at least one of these discrete gradations in shaft diameter forms
a spray-off edge for removing lubricant from the shaft;
at least one rolling-contact bearing, to be lubricated by the liquid
lubricant, mounted adjacent the inlet portion of the shaft within the
stationary housing for supporting the rotatably mounted shaft therein,
wherein each rolling-contact bearing defines a second axis central to the
roller bearing;
a bearing collar adjacent each rolling-contact bearing and defining a
protrusion extending away from the first axis and toward the second axis,
said protrusion being located on the end of the bearing collar adjacent
the inlet portion of the shaft, wherein each bearing collar defines a
spray-off edge for removing lubricant from a respective rolling-contact
bearing;
a seal member mounted around the shaft and coupled to the stationary
housing, wherein the seal member defines, adjacent to the inlet portion of
the shaft, an annular rim which is separated by a distance along the axis
of the shaft from the protrusion of each bearing collar, wherein at least
a portion of said annular rim and a corresponding portion of said
protrusion are located substantially equidistant from said first axis,
said separation defining a radially extending inlet for the liquid
lubricant;
a plurality of chambers formed in the seal member, said chambers being
disposed between the inlet and outlet portions of the shaft and opening
onto the surface of the shaft, wherein each chamber projects into the seal
member in a direction substantially away from the first axis, and wherein
at least one of the chambers is located adjacent a spray-off edge for
receiving lubricant removed from the shaft at the spray-off edge;
a plurality of drain ports for the liquid lubricant, each drain port
corresponding to a respective chamber defined at the seal member; and
an outlet for the liquid lubricant having a diameter substantially equal to
that of the inlet for the liquid lubricant.
9. The sealing apparatus according to claim 8, wherein the outlet for the
liquid lubricant is formed between a surface defined by the seal member
and a protrusion of the shaft.
10. The sealing arrangement according to claim 8, wherein the seal member
further defines, adjacent the annular rim defined by the labyrinth seal
member and in liquid communication with the inlet, a groove for collecting
liquid lubricant, said groove being dimensioned based on the quantity of
liquid lubricant that is centrifuged off at the inlet through the rotation
of the shaft.
11. The sealing apparatus according to claim 8, wherein the size of each
chamber in the seal member is dimensioned to be large enough to
accommodate the maximum amount of liquid lubricant present, at each
chamber's respective location along the shaft, during operation of the
machine.
12. The sealing arrangement according to claim 11, wherein the seal member
further defines, adjacent the annular rim defined by the labyrinth seal
member and in liquid communication with the inlet, a groove for collecting
liquid lubricant, said groove being dimensioned based on the quantity of
liquid lubricant that is centrifuged off at the inlet through the rotation
of the shaft.
13. The sealing apparatus according to claim 8, wherein the machine is
powered by electricity.
14. The sealing apparatus according to claim 8, wherein at least one of the
rolling-contact bearings is a rolling-contact bearing of the N type of
construction.
Description
BACKGROUND OF THE INVENTION
The invention relates to a sealing arrangement for retaining liquid
lubricant in selected areas of a machine.
Such a sealing arrangement is disclosed by the DE-U-87 15 621. This sealing
arrangement is comprised of a labyrinth seal and several separate
structural members, whose function it is to spray off the oil that has
penetrated into the sealing gap.
The object of the invention is to further develop a sealing arrangement of
the type described at the outset to render possible an effective sealing
[action] using a one-piece labyrinth seal member.
SUMMARY OF THE INVENTION
The present invention is directed to a sealing apparatus for retaining
liquid lubricant in selected areas of a machine. The apparatus comprises a
shaft rotatably mounted, for rotation relative to a stationary housing.
The shaft defines inlet and outlet portions separated axially along the
shaft, and the shaft diameter increases in at least one discrete gradation
between the inlet and outlet portions of the shaft. These gradations
provide spray-off edges each of which directs lubricant to a respective
chamber, or plurality of chambers, and, subsequently, to a respective
drain port, in a seal. The seal is mounted around the shaft and coupled to
the stationary housing and defines, adjacent to the inlet portion of the
shaft, an annular rim.
The sealing apparatus according to the present invention further comprises
at least one rolling-contact bearing for supporting the rotatably mounted
shaft. Each rolling-contact bearing is lubricated by the liquid lubricant,
and is mounted adjacent the inlet portion of the shaft within the
stationary housing. A bearing collar is coupled to each rolling-contact
bearing and defines a protrusion which extends toward the second axis on
the end of the bearing collar adjacent the inlet portion of the shaft.
This protrusion is separated by a distance along the axis of the shaft
from the annular rim. This separation thereby defines an inlet for the
liquid lubricant.
The seal member further defines an outlet for the liquid lubricant between
the seal member and a corresponding surface on the shaft formed by one of
the discrete increases in the diameter of the shaft. The seal and the
corresponding surface on the shaft are separated by a distance
substantially equal to that between the annular rim and the protrusion of
each roller bearing. By providing an inlet and an outlet of substantially
the same size the pressure differential between the openings is
eliminated.
A bearing collar situated on the inner ring of the rolling-contact bearing
provides a very effective spray-off edge. This spray-off edge enables a
very large portion of the oil emerging out of the bearing to be
centrifuged off and thus kept away from the inlet slit of the labyrinth
seal. Due to the fact that the inlet and outlet slits of the labyrinth
seal have the same diameter, no pressure differences develop between the
inlet and outlet side of the labyrinth seal which could result in oil
being delivered. Consequently, an adequate sealing action is attained by
means of the individual sealing gaps of the labyrinth seal.
Adjoining the annular rim of the labyrinth seal, it is advantageous to have
an oil-collecting groove at the periphery of the labyrinth seal member.
The size of the oil-collecting groove is dimensioned in dependence upon
the quantity of oil that is centrifuged off at the radial gap. This also
ensures that the oil that is centrifuged off is kept away from the inlet
slit of the labyrinth seal. The way the oil-collecting groove is designed
inevitably results in a relatively long axial gap in the inlet area of the
labyrinth seal. The sealing action is likewise improved as a result.
As the shaft rotates oil is sprayed off the shaft at each grading in shaft
diameter. The quantity of oil sprayed off at these gradings decreases as
the distance from the inlet increases.
The volume of each chamber, each of which is dimensioned in accordance with
the quantity of oil that accumulates, ensures that the oil in each chamber
can be completely accommodated and will not be pressed further to the
outside. The volume of the chambers can thereby diminish toward the outlet
side, so that one can economize on the [amount of] space needed for the
labyrinth seal.
Roller bearings of the N type of construction already come equipped with a
bearing collar on the inner ring. Thus, a special bearing design is not
needed to provide the necessary bearing collar.
The object of the invention shall be clarified in greater detail in the
following based on an exemplified embodiment depicted in the drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows a cross-section of a seal embodying the present invention.
DETAILED DESCRIPTION
1 designates the stator and 2 the rotor of an electrical motor. The shaft 3
of the rotor 2 is supported by means of a roller bearing 4 of the N type
of construction in a bearing bracket 5, which is secured to the motor
housing. These types of roller bearings feature a bearing collar 7 on the
inner ring 6. Towards the side of the rotor, the bearing bore which
accommodates the roller bearing 4 is sealed by a labyrinth seal 8 that
functions as a bearing cover.
An annular rim 9, which extends parallel to the bearing collar 7 of the
roller bearing 4, is formed on the body of the labyrinth seal 8. The axial
extent of the labyrinth seal 8 is dimensioned so that, together with the
bearing collar 7, the annular rim 9 forms a narrow, radial inlet slit 10.
Adjoining the annular rim 9, an oil-collecting groove 11 is formed on the
periphery of the body of the labyrinth seal 8. Oil that is centrifuged off
from the bearing collar 7 to the outside is collected in this
oil-collecting groove 11 and flows off in a downward direction. The
formation of this oil-collecting groove 11 results in a relatively long
axial gap 12 in the inlet area of the labyrinth seal 8. This axial gap
hinders a passage of the oil.
Adjoining this axial gap 12 and provided in the body of the labyrinth seal
8, is a first chamber 13. A first grading 14 of the shaft 3 is allocated
to this first chamber 13. The shaft grading 14 forms a spray-off edge,
through which means the oil that has advanced up to this edge is
centrifuged off into the first chamber 13. The oil flows from the walls of
this chamber 13 through a drain port 15 toward a collecting channel 16.
This collecting channel 16 discharges into the space of a gear housing
which is connected to the motor housing and is not depicted in the
drawing. Only the pinion 17 that is connected to the shaft 3 is shown from
the gear unit.
A second chamber 18 and contiguous to this, additional chambers 19 are
formed in the body of the labyrinth seal 8 and are set apart axially from
the first chamber 13. A second grading 20 of the shaft 3 is allocated to
the second chamber 19. No further shaft gradings are provided in the area
of the additional chambers 19. However, it is possible to introduce
gradings on the shaft 3 in this area as well.
The outlet slit 21 of the labyrinth seal 8 is formed between an axially
protruding rim 22 premolded on the body of the labyrinth seal 8 and the
one front end 23 of the rotor 2. Where the outlet slit 21 ends, it has the
same diameter as the inlet slit 10. In this manner, pressure differences
between the inlet and outlet side of the labyrinth seal 8 are avoided and,
consequently, one obtains a labyrinth which is substantially neutral with
respect to delivery.
In the described sealing arrangement, structural members which exist in any
case, such as the roller bearing 4 and the shaft 3, are constructed
together with the labyrinth seal 8 in a way which allows a very effective
sealing action to be achieved. Thus, additional structural parts are not
needed.
There are various changes and modifications which may be made to the
invention as would be apparent to those skilled in the art. However, these
changes or modifications are included in the teaching of the disclosure,
and it is intended that the invention be limited only by the scope of the
claims appended hereto.
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